1. Field of Invention
This invention relates to improved control linkage for the upper rotor of coaxial counterrotating helicopter rotors by means of which collective and cyclic pitch is transmitted from a conventional swashplate to the horns of the upper rotor blades.
2. Description of the Prior Art
Prior to this invention it has been the practice to react the torque in the rotatable and non-rotatable swashplate elements by means of scissors, the scissors for the non-rotatable element of the swashplate being connected between the non-rotatable swashplate element and adjacent fixed structure, for example, the transmission housing, and the scissors for the rotatable element of the swashplate being connected between the rotatable swashplate element and a rotatable element of the main rotor drive shaft. However, in coaxial rotor helicopters the presence of the lower rotor makes it desirable to locate the blade pitch control linkage for the upper rotor within the rotor drive shaft and move the blade pitch control horns internal to the rotor drive shaft. The use of conventional non-rotatable and rotatable scissors in a system where centrally located blade pitch control rods are actuated by a plurality of servos located at a radial distance far from the blade horns and their control linkage required additional parts and joints which resulted in increased weight and cost.